The sum of first five multiples of 3 is..

The sum of first five multiples of 3 is: A. 45 B. 65 C. 75 D. 90 Answer: Option A Show Answer Solution(By Apex Team) $\begin{aligned}S_n&=[2a+(n-1)d]\times\frac{n}{2}\\ \Rightarrow S_5&=[2\times3+(5-1)3]\times\frac{5}{2}\\ \Rightarrow S_5&=[6+12]\times\frac{5}{2}\\…